Substrate processing apparatus and method of transferring substrate

ABSTRACT

There is provided a substrate processing apparatus having a transfer arm configured to transfer two substrates between a transfer chamber and a processing chamber having two mounting tables, the transfer arm holding the two substrates in a state where the two substrates overlap each other with a gap between the two substrates. The substrate processing apparatus includes: a lower substrate detection sensor configured to detect an edge portion of a lower substrate when the lower substrate is transferred; and an upper substrate detection sensor configured to detect an edge portion of an upper substrate when the upper substrate is transferred.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority fromJapanese Patent Application No. 2016-183132, filed on Sep. 20, 2016, theentire contents of which are incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to a substrate processing apparatus and amethod of transferring a substrate, wherein two substrates are loadedinto one processing chamber.

BACKGROUND

In a substrate processing apparatus for performing predeterminedprocessing, for example, chemical oxide removal (COR) processing or postheat treatment (PHT) processing on a semiconductor wafer (hereinafter,simply referred to as “wafer”) as a substrate, a plurality of processmodules serving as processing chambers are arranged around a transfermodule which is a common transfer chamber. While one wafer istransferred to one process module, the COR processing or PHT processingis performed on another wafer in another process module, therebyimproving efficiency of the processing. In particular, since the CORprocessing or the PHT processing is a time-consuming process, two wafersare accommodated in each of the process modules, and the COR processingor the PHT processing is simultaneously performed on the two wafers.

In such a substrate processing apparatus, it is necessary tosimultaneously transfer two wafers toward each process module, and thus,a transfer arm disposed within the transfer module holds the two wafersusing a pick part installed at a tip of the transfer arm such that thetwo wafers overlap each other with a gap between the two wafers. Here,if the transfer arm holds only one wafer due to failure ofdelivery/reception of wafers or the like, only one wafer is loaded intoeach process module, so that the efficiency of the COR processing or PHTprocessing is lowered. Therefore, it is necessary to confirm whether thetransfer arm holds two wafers before the wafers are loaded into eachprocess module.

Accordingly, there is proposed a method of confirming whether thetransfer arm holds two wafers. Specifically, a sensor including alight-emitting part for emitting laser light or red LED light and alight-receiving part is disposed in front of each process module withinthe transfer module. Each wafer held by the transfer arm is irradiatedwith the laser light or red LED light from the light-emitting part, andthe light-receiving part detects whether the laser light or red LEDlight is blocked by the wafer, thereby confirming whether the transferarm holds two wafers. At this time, since each wafer is obliquelyirradiated with the laser light or red LED light from the light-emittingpart, it is possible to confirm the presence of each wafer even thoughthe transfer arm holds the two wafers while overlapping with each other.

Meanwhile, each process module has a stage for mounting each waferthereon. If the wafer is not mounted at a correct location with respectto the stage, this is determined as an error and processing may beinterrupted, so that it is necessary to correct a position of the waferbefore the wafer is loaded into each process module. Conventionally, anorienter which is a position alignment device is provided to a loadermodule which is a standby transfer chamber connected to the transfermodule, and the position of the wafer is corrected in the orienter. Inthis case, since it is necessary to reciprocate the wafer between thetransfer module and the loader module, the efficiency of processingremarkably deteriorates. Therefore, it has been strongly required tocorrect the position of the wafer when the wafer is loaded from thetransfer module into each process module.

However, in the aforementioned method, only one point on an edge of eachwafer is detected by the sensor. If only one point on the edge isdetected, a center position of the wafer cannot be specified so that theposition of the wafer cannot be corrected.

SUMMARY

Some embodiments of the present disclosure provide a substrateprocessing apparatus and a method of transferring a substrate, whereinrespective positions of two substrates arranged to overlap each othercan be accurately specified.

According to one embodiment of the present disclosure, there is provideda substrate processing apparatus having a transfer arm configured totransfer two substrates between a transfer chamber and a processingchamber having two mounting tables, the transfer arm holding the twosubstrates in a state where the two substrates overlap each other with agap between the two substrates, the substrate processing apparatusincluding: a lower substrate detection sensor configured to detect anedge portion of a lower substrate of the two substrates when the lowersubstrate is transferred; and an upper substrate detection sensorconfigured to detect an edge portion of an upper substrate of the twosubstrates when the upper substrate is transferred, wherein the transferarm transfers the lower substrate between one of the mounting tables andthe transfer chamber and transfers the upper substrate between the otherof the mounting tables and the transfer chamber, the lower substratedetection sensor is an optical sensor having a light-emitting part and alight-receiving part, one of the light-emitting part and thelight-receiving part is disposed in a region through which the lowersubstrate passes when the lower substrate is transferred, and isdisposed to be placed between the lower substrate and the uppersubstrate, the other of the light-emitting part and the light-receivingpart is disposed to face the one of the light-emitting part and thelight-receiving part with the lower substrate interposed between thelight-emitting part and the light-receiving part when the lowersubstrate is transferred, and the upper substrate detection sensor isdisposed in a region through which the upper substrate passes when theupper substrate is transferred.

According to another embodiment of the present disclosure, there isprovided a method of transferring two substrates between a transferchamber and a processing chamber having two mounting tables by using atransfer arm, including: holding the two substrates by the transfer armin a state where the two substrates overlap each other with a gapbetween the two substrates; transferring a lower substrate of the twosubstrates by the transfer arm between one of the mounting tables andthe transfer chamber; and transferring an upper substrate of the twosubstrates by the transfer arm between the other of the mounting tablesand the transfer chamber, wherein a lower substrate detection sensorconfigured to detect an edge portion of the lower substrate when thelower substrate is transferred, and an upper substrate detection sensorconfigured to detect an edge portion of the upper substrate when theupper substrate is transferred are disposed, the lower substratedetection sensor is an optical sensor having a light-emitting part and alight-receiving part, one of the light-emitting part and thelight-receiving part is disposed in a region through which the lowersubstrate passes when the lower substrate is transferred, and isdisposed to be placed between the lower substrate and the uppersubstrate, the other of the light-emitting part and the light-receivingpart is disposed to face the one of the light-emitting part and thelight-receiving part with the lower substrate interposed between thelight-emitting part and the light-receiving part when the lowersubstrate is transferred, and the upper substrate detection sensor isdisposed in a region through which the upper substrate passes when theupper substrate is transferred.

BRIEF DESCRIPTION OF DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate embodiments of the presentdisclosure, and together with the general description given above andthe detailed description of the embodiments given below, serve toexplain the principles of the present disclosure.

FIG. 1 is a plan view schematically showing a configuration of asubstrate processing apparatus according to an embodiment of the presentdisclosure.

FIGS. 2A and 2B are views illustrating a configuration of a transfer armin FIG. 1.

FIGS. 3A to 3E are process views illustrating transfer of wafers towardan interior of a process module by the transfer arm.

FIGS. 4A and 4B are views illustrating a communication port forcommunicating an interior of the transfer module with the interior ofthe process module.

FIG. 5 is an enlarged sectional view schematically showing aconfiguration of a lower wafer detection sensor in FIGS. 4A and 4B.

FIGS. 6A to 6C are process views illustrating a method of mounting thelower wafer detection sensor to a flange.

FIGS. 7A to 7D are process views illustrating a method of transferringsubstrates according to an embodiment of the present disclosure.

FIGS. 8A to 8D are process views illustrating the method of transferringsubstrates according to the embodiment of the present disclosure.

FIG. 9 is a view illustrating a method of specifying a center positionof a circle.

FIG. 10 is a view illustrating a height sensor disposed in a load lockmodule.

FIG. 11 is a view illustrating a monitor included in the substrateprocessing apparatus in FIG. 1.

DETAILED DESCRIPTION

Reference will now be made in detail to various embodiments, examples ofwhich are illustrated in the accompanying drawings. In the followingdetailed description, numerous specific details are set forth in orderto provide a thorough understanding of the present disclosure. However,it will be apparent to one of ordinary skill in the art that the presentdisclosure may be practiced without these specific details. In otherinstances, well-known methods, procedures, systems, and components havenot been described in detail so as not to unnecessarily obscure aspectsof the various embodiments.

First, one embodiment of the present disclosure will be described.

FIG. 1 is a plan view schematically showing a configuration of asubstrate processing apparatus according to an embodiment of the presentdisclosure. For the sake of easy understanding, a portion of theinternal components of the substrate processing apparatus aretransmitted and shown in FIG. 1.

In FIG. 1, the substrate processing apparatus 10 includes a waferstorage part 11 for storing a plurality of wafers W therein, a commontransfer part (transfer module) 12 serving as a transfer chamber forsimultaneously transferring two wafers W, and a plurality of substrateprocessing parts (process modules) 13 serving as processing chambers inwhich predetermined processing, for example, COR processing or PHTprocessing is performed on the wafers W transferred from the transfermodule 12. Interior portions of the process module 13 and the transfermodule 12 are maintained in a vacuum atmosphere.

In the substrate processing apparatus 10, two selected wafers W amongthe plurality of wafers W stored in the wafer storage part 11 are heldto overlap each other by a transfer arm 14 a or 14 b included in thetransfer module 12, and the transfer arm 14 a or 14 b is moved so thateach of the wafers W is transferred within the transfer module 12 andmounted on each of two stages 15 a and 15 b (mounting table) disposedinside the process module 13. Subsequently, in the substrate processingapparatus 10, after predetermined processing is performed on therespective wafers W mounted on the stages 15 a and 15 b in the processmodule 13, the two processed wafers W are held to overlap each other bythe transfer arm 14 a or 14 b and then unloaded to the wafer storagepart 11 by moving the transfer arm 14 a or 14 b.

The wafer storage part 11 includes load ports 17 a to 17 c which aremounting tables for FOUPs 16 a to 16 c serving as containers for storingthe plurality of wafers W, a loader module 18 for receiving the storedwafer W from the FOUP 16 a, 16 b or 16 c mounted on the load port 17 a,17 b or 17 c or delivering the wafer W subjected to the predeterminedprocessing in the process module 13 to the FOUP 16 a, 16 b or 16 c, andload lock modules 19 a and 19 b for temporarily holding the wafer W inorder to receive and deliver the wafer W between the loader module 18and the transfer module 12.

The loader module 18 is composed of a rectangular shaped housing havingan interior maintained at atmospheric pressure, and the plurality ofload ports 17 a, 17 b and 17 c are arranged in parallel in one sidesurface constituting a long side of the rectangle. The loader module 18has a transfer arm (not shown) which is movable therein in alongitudinal direction of the rectangle. The transfer arm transfers thewafer W from the FOUPs 16 a, 16 b and 16 c mounted on the load port 17a, 17 b and 17 c to the load lock module 19 a, or unloads the wafer Wfrom the load lock module 19 b to the FOUPs 16 a, 16 b and 16 c. TheFOUPs 16 a, 16 b and 16 c accommodate a plurality of wafers W that areplaced at equal intervals while overlapping each other. Interiors of theFOUPs 16 a, 16 b and 16 c mounted on the load port 17 a, 17 b and 17 care usually filled with atmospheric air, but may be filled with nitrogengas or the like and then air-tightly sealed.

The load lock module 19 a temporarily holds the wafer W so as to handover the wafer W accommodated in the FOUPs 16 a, 16 b and 16 c mountedon the load port 17 a, 17 b and 17 c having an interior maintained atatmospheric pressure, to the process module 13 having an interiormaintained at a vacuum atmosphere. The load lock module 19 a has anupper stocker 20 a and a lower stocker 20 b which hold two wafers Wwhile making the two wafers W overlap each other. The load lock module19 a further has a gate valve 21 a for securing airtightness withrespect to the loader module 18 and a gate valve 21 b for securingairtightness with respect to the transfer module 12. Furthermore, a gasintroduction system and a gas exhaust system (not shown) are connectedto the load lock module 19 a via a pipeline, so that interior of theload lock module is controlled to be in an atmospheric pressureatmosphere or a vacuum atmosphere by the gas introduction system and thegas exhaust system. The load lock module 19 b has the same configurationas the load lock module 19 a.

The transfer module 12 transfers an unprocessed wafer W from the waferstorage part 11 to the process module 13 and unloads the processed waferW from the process module 13 to the wafer storage part 11. The transfermodule 12 is composed of a housing which is in the shape of a rectangleand of which interior is maintained in a vacuum atmosphere. The transfermodule 12 includes transfer arms 14 a and 14 b each of which holds twowafers W while making the two wafers W overlap each other, a rotarytable 22 for rotatably supporting the transfer arms 14 a and 14 b, arotary mounting table 23 with the rotary table 22 mounted thereon, andguide rails 24 for movably guiding the rotary mounting table 23 in alongitudinal direction of the transfer module 12. The transfer module 12communicates with the load lock modules 19 a and 19 b of the waferstorage part 11 and the respective process modules 13 via the gatevalves 21 a and 21 b as well as gate valves 25 a to 25 f to be describedlater. In the transfer module 12, the transfer arm 14 a receives twooverlapping wafers W which are held in the overlapping state by theupper stocker 20 a and the lower stocker 20 b in the load lock module 19a, and then transfers the wafers to each process module 13. Further, thetransfer arm 14 b holds the two wafers W, which have been subjected toprocessing in the process module 13, while making the two wafers Woverlap each other and unloads the two wafers W to the load lock module19 b.

FIGS. 2A and 2B are views illustrating a configuration of the transferarm in FIG. 1. FIG. 2A is a perspective view showing the entire transferarm. FIG. 2B is a side view of a pick part of the transfer arm.

In FIGS. 2A and 2B, the transfer arm 14 a and the transfer arm 14 b havepick parts 24 a and 24 b at tips thereof, respectively, to mount twowafers W on each of the pick parts. The transfer arm 14 a has a linkmechanism in which a plurality of rectangular link portions (linkages)are rotatably connected to one another at a plurality of joint(articulation) portions. One end of the link mechanism of the transferarm 14 a is rotatably supported by the rotary table 22. The other end ofthe link mechanism of the transfer arm 14 a is a free end, and the pickpart 24 a is connected to the other end (FIG. 2A).

The pick part 24 a has a configuration in which an upper pick 24 at anda lower pick 24 ab having a bifurcated fork shape are stacked and spacedapart from each other by a predetermined distance t (FIG. 2B). In thepick part 24 a, one wafer W is mounted on an upper surface of the upperpick 24 at and one wafer W is also mounted on an upper surface of thelower pick 24 ab (between the upper pick 24 at and the lower pick 24ab). In other words, the transfer arm 14 a holds the two wafers W byusing the pick part 24 a in a state where the two wafers W overlap eachother with a gap between the two wafers W. The pick part 24 b has aconfiguration in which an upper pick 24 bt and a lower pick 24 bb havinga bifurcated fork shape are stacked and spaced apart from each other bya predetermined distance t, and has the same configuration as the pickpart 24 a.

Due to rotation of the one end of the link mechanism and movement of theother end of the link mechanism, the transfer arm 14 a transfers therespective wafers W mounted on the pick part 24 a formed at the otherend to a desired location. Furthermore, the transfer arm 14 b has thesame configuration as the transfer arm 14 a. Since two wafers W aremounted on the transfer arms 14 a and 14 b at the same time, thesubstrate processing apparatus 10 can simultaneously transfer fourwafers W using the transfer arms 14 a and 14 b. The rotary table 22rotatably supports the transfer arms 14 a and 14 b about a verticalrotation axis.

Turning to FIG. 1, the rotary mounting table 23 and the guide rails 24constitute a sliding mechanism for moving the mounted rotary table 22 inthe longitudinal direction in the transfer module 12.

The respective process modules 13 communicate with the transfer module12 via the gate valves 25 a to 25 f. Therefore, the gate valves 25 a to25 f allow securement of airtightness between each process module 13 andthe transfer module 12 and communication therebetween. Further, a gasintroduction system (a supply source of a gas such as a processing gas,a purge gas and the like) and a gas exhaust system (a vacuum pump, anexhaust control valve, an exhaust pipe and the like) which are not shownin the figures are connected to the process modules 13.

Each process module 13 has the stages 15 a and 15 b (two mountingtables) for mounting two wafers W thereon in a state where the wafersare arranged in a horizontal direction. Each process module 13 uniformlyand simultaneously processes surfaces of the two wafers W by mountingthe wafers W in the arranged state on the stages 15 a and 15 b. In thisembodiment, each of the plurality of process modules 13 performs any oneof COR processing and PHT processing.

The substrate processing apparatus 10 further includes a controller 26as a control part. The controller 26 executes a program stored in amemory incorporated therein to control operations of respectivecomponents of the substrate processing apparatus 10.

FIGS. 3A to 3E are process views illustrating transfer of wafers towardthe interior of the process module by the transfer arm.

First, the transfer arm 14 a which holds the two wafers W while makingthe two wafers W overlap each other is moved to the front of one processmodule 13 (FIG. 3A). The link mechanism of the transfer arm 14 a extendssuch that the pick part 24 a enters the process module 13 and causes thewafer W mounted on the lower pick 24 ab (hereinafter, referred to as“lower wafer W”) to face the stage 15 a (FIG. 3B). At this time, thestage 15 a receives the lower wafer W using lift pins or the like (notshown) and mounts the lower wafer W on an upper surface of the stage 15a (a first transfer step). Thereafter, due to retraction of the linkmechanism, the pick part 24 a of the transfer arm 14 a is withdrawn fromthe interior of the process module 13 (FIG. 3C). At this time, the pickpart 24 a holds only the wafer W mounted on the upper pick 24 at(hereinafter, referred to as “upper wafer W”).

Subsequently, the link mechanism of the transfer arm 14 a extends suchthat the pick part 24 a enters the process module 13 again and causesthe upper wafer W to face the stage 15 b (FIG. 3D). At this time, thestage 15 b receives the upper wafer W using the lift pins or the like(not shown) and mounts the upper wafer W on an upper surface of thestage 15 b (a second transfer step). Thereafter, due to the retractionof the link mechanism, the pick part 24 a of the transfer arm 14 a iswithdrawn from the interior of one process module 13 (FIG. 3E). At thistime, the pick part 24 a holds no wafer W.

Meanwhile, in the substrate processing apparatus 10, if each wafer W isnot mounted at a correct location on the stage 15 a or 15 b, it isdetermined as an error and processing in each process module 13 isinterrupted. Therefore, it is necessary to accurately specify theposition of the wafer W before the wafer W is transferred to eachprocess module 13 and to correct a position of the wafer W if theposition of the wafer W is misaligned from a desired position. Inparticular, from the viewpoint of prevention of degradation ofthroughput, it is preferable to specify the position of the wafer W andto modify the position of the wafer W when the wafer W is transferred bythe transfer arms 14 a and 14 b (in particular, the step shown in FIG.3B or 3D). Correspondingly, as will be described later, in the presentembodiment, a sensor for detecting an edge portion (edge) of the wafer Wis installed in front of each process module 13, so that the sensordetects two points on the edge portion of the wafer W so as to specifythe position of the wafer W when the wafer is transferred into theprocess module 13 by the transfer arms 14 a and 14 b.

FIGS. 4A and 4B are views illustrating a communication port forcommunicating the interior of the transfer module with the interior ofthe process module. FIG. 4A is a sectional view taken along line V-V inFIG. 1. FIG. 4B is a sectional view taken along line I-I in FIG. 4A.Specifically, FIG. 4A shows a vertical cross section of a communicationport 27 provided in a wall portion of the transfer module 12 and FIG. 4Bshows a horizontal cross section of the communication port 27.

In FIG. 1, the communication port 27 (opening) for communicating theinterior of the transfer module 12 with the interior of each processmodule 13 is formed in the wall portion of the transfer module 12.Moreover, the gate valves 25 a to 25 f are interposed between thecommunication ports 27 and the process modules 13, respectively. Sincethe respective communication ports 27 and the interior of the transfermodule 12 communicate with each other, interiors of the communicationports 27 are maintained in a vacuum atmosphere.

The communication port 27 is an elongated hole of which the crosssection extends along the longitudinal direction (hereinafter, referredto as “horizontal direction”) of the transfer module 12 and issurrounded by a container-shaped flange 28 protruding from the wallportion of the transfer module 12. A width L of the communication port27 is smaller than a total width 2D of two wafers W when the two wafersW are arranged in the horizontal direction. Therefore, it is impossibleto transfer the two wafers W to the interior of the process module 13 inthe state where the two wafers W are arranged in the horizontaldirection.

A lower wafer detection sensor 29 for detecting an edge (edge portion)of the lower wafer W and an upper wafer detection sensor 30 fordetecting an edge portion of the upper wafer W are arranged in theflange 28. The lower wafer detection sensor 29 is an optical sensorhaving a set of a light-emitting part 29 a and a light-receiving part 29b. The light-receiving part 29 b receives laser light or red LED lightemitted from the light-emitting part 29 a. In the flange 28, when viewedfrom above along a direction in which the lower wafer W and the upperwafer W overlap each other (hereinafter, referred to as “overlappingdirection”), the light-emitting part 29 a is disposed in a regionthrough which the lower wafer W passes when the lower wafer W istransferred toward the interior of the process module 13, and is alsodisposed to be placed between the lower wafer W and the upper wafer Wwhen the lower wafer W is transferred toward the interior of the processmodule 13; and the light-receiving part 29 b is disposed to face thelight-emitting part 29 a with the lower wafer W interposed between thelight-receiving part 29 b and the light-emitting part 29 a. In the lowerwafer detection sensor 29, only the lower wafer W passes between thelight-emitting part 29 a and the light-receiving part 29 b, and theupper wafer W does not pass between the light-emitting part 29 a and thelight-receiving part 29 b. In the lower wafer detection sensor 29,blockage of the laser light or red LED light when the edge portion ofthe lower wafer W passes between the light-emitting part 29 a and thelight-receiving part 29 b is detected, thereby detecting passage of theedge portion of the lower wafer W between the light-emitting part 29 aand the light-receiving part 29 b. A position of the edge portion of thelower wafer W that has blocked the laser light or red LED light isspecified based on an encoder value of a motor of the transfer arm 14 aat this time or a position of the lower wafer detection sensor 29.

The upper wafer detection sensor 30 is also an optical sensor having aset of a light-emitting part 30 a and a light-receiving part 30 b. Inthe flange 28, when viewed from above along the overlapping direction,the upper wafer detection sensor 30 is disposed in a region throughwhich the upper wafer W passes when the upper wafer W is transferredtoward the stage 15 b. Further, the light-emitting part 30 a and thelight-receiving part 30 b are provided on the flange 28 to face eachother with the communication port 27 interposed between thelight-emitting part 30 a and the light-receiving part 30 b. In the upperwafer detection sensor 30, the upper wafer W passes between thelight-emitting part 30 a and the light-receiving part 30 b. Moreover,since the pick part 24 a of the transfer arm 14 a does not hold thelower wafer W when the upper wafer W is transferred toward the stage 15b, the lower wafer W does not pass between the light-emitting part 30 aand the light-receiving part 30 b. In the upper wafer detection sensor30, the blockage of the laser light or red LED light when the edgeportion of the upper wafer W passes between the light-emitting part 30 aand the light-receiving part 30 b is detected, thereby detecting passageof the edge portion of the upper wafer W between the light-emitting part30 a and the light-receiving part 30 b. A position of the edge portionof the upper wafer W that has blocked the laser light or red LED lightis specified based on the encoder value of the motor of the transfer arm14 a at this time or a position of the upper wafer detection sensor 30.

In the flange 28, the light-receiving part 29 b, the light-emitting part30 a and the light-receiving part 30 b are disposed outside thecommunication port 27 and directed to an interior of the communicationport 27 through respective sensor windows 31 provided on the flange 28or a bracket 32 to be described later. Since the light-emitting part 29a is positioned between the lower wafer W and the upper wafer W when thelower wafer W is transferred toward the interior of the process module13, the light-emitting part 29 a is disposed within the communicationport 27, i.e., in a vacuum atmosphere.

FIG. 5 is an enlarged sectional view schematically showing theconfiguration of the lower wafer detection sensor in FIGS. 4A and 4B.

In FIG. 5, the lower wafer detection sensor 29 includes the cup-shapedbracket 32; the light-emitting part 29 a which is bent in an invertedL-shape when viewed from a side and radiates the laser light 1 (or redLED light) downward in the figure from a tip thereof; thelight-receiving part 29 b which is provided outside of and at a bottomof the bracket 32 and faces the tip of the light-emitting part 29 a viathe sensor window 31; and an assembly member 33 for supporting andholding the light-emitting part 29 a. The assembly member 33 is mountedinside of and on the bracket 32 via a shim 34. In other words, since thelight-emitting part 29 a is elevated and held by the shim 34 and theassembly member 33 from the bracket 32, the light-emitting part 29 aprotrudes upward from the bracket 32. A size of an opening 32 a of thebracket 32 corresponds to a size of a sensor port 28 a formed on a lowerside of the flange 28. The lower wafer detection sensor 29 is mounted onthe flange 28 by installing the bracket 32 below the flange 28 such thatthe opening 32 a and the sensor port 28 a face each other. As describedabove, since the light-emitting part 29 a protrudes upward from thebracket 32, when the lower wafer detection sensor 29 is mounted on theflange 28, the light-emitting part 29 a protrudes into the interior ofthe communication port 27. Accordingly, the light-emitting part 29 a isdisposed to be placed between the lower wafer W and the upper wafer W.

Further, when viewed along an installation direction (a verticaldirection in the figure) of the lower wafer detection sensor 29, thesize of the light-emitting part 29 a is set so as not to protrude fromthe opening 32 a of the bracket 32, in other words, not to protrude fromthe sensor port 28 a of the flange 28. Accordingly, when the lower waferdetection sensor 29 is mounted on the flange 28, the light-emitting part29 a does not interfere with the flange 28.

In the lower wafer detection sensor 29, an adhesive having low-degassingproperty is provided to bond the components thereof, and the assemblymember 33 or the shim 34 is formed of low-carbon stainless steel, e.g.,SUS 316L. Accordingly, it is possible to prevent an adverse influence onthe processed wafer W due to a gas or carbon released from the lowerwafer detection sensor 29. In addition, the tip of the light-emittingpart 29 a is composed of a heat resistant member, e.g., a member havinga heat resistant temperature of 300 degrees C. or higher. This makes itpossible to inhibit the tip of the light-emitting part 29 a from beingthermally deformed by radiant heat from the lower or upper wafer W,thereby preventing the laser light (or red LED light) 1 from beingunable to be radiated toward the light-receiving part 29 b. Further, alight-received amount monitor 35 for measuring a received amount of thelaser light (or red LED light) 1 is connected to the light-receivingpart 29 b. When the received amount of the laser light (or red LEDlight) 1 is decreased due to a deposition adhered to the light-emittingpart 29 a or the light-receiving part 29 b so that the received amountfalls below a predetermined threshold value, the light-received amountmonitor 35 issues a warning, which urges a user to pay attention tocleaning, to the controller 26 or issues a signal for requestinginterruption of the transfer of the lower wafer W. Although thelight-emitting part 29 a is disposed above the light-receiving part 29 bin the lower wafer detection sensor 29, there is no particularlimitation on a vertical positional relationship between thelight-emitting part 29 a and the light-receiving part 29 b. For example,the light-emitting part 29 a may be disposed below the light-receivingpart 29 b.

FIGS. 6A to 6C are process views illustrating a method of mounting thelower wafer detection sensor to the flange.

First, after the light-emitting part 29 a is mounted on the bracket 32,a height of the light-emitting part 29 a is measured in a state wherethe shim 34 is not disposed between the assembly member 33 and thebracket 32 (FIG. 6A), and the shim 34 having a required thickness isselected. Subsequently, the assembly member 33 is installed on thebracket 32 via the selected shim 34 (FIG. 6B). Thereafter, the bracket32 is installed on the lower side of the flange 28 such that the opening32 a and the sensor port 28 a face each other, whereby the lower waferdetection sensor 29 is mounted on the flange 28 (FIG. 6C). As describedabove, the size of the light-emitting part 29 a is set so as not toprotrude from the sensor port 28 a of the flange 28 when viewed alongthe installation direction of the lower wafer detection sensor 29, andthe bracket 32 is also installed on the flange 28 in the state where thelight-emitting part 29 a and the light-receiving part 29 b are mountedon the bracket 32, so that the lower wafer detection sensor 29 can beeasily mounted on the flange 28 in a simple process.

FIGS. 7A to 7D and 8A to 8D are process views illustrating a method oftransferring substrates according to an embodiment of the presentdisclosure. In order to clearly distinguish the wafer W from the stages15 a and 15 b in FIGS. 7A to 7D and 8A to 8D, the stages 15 a and 15 bare indicated by crosshatching. In FIGS. 7A to 7D and 8A to 8D, thetransfer arm 14 a, the process module 13 and the transfer module 12 arenot shown.

Curves C₁ and C₂ indicated by thin broken lines in FIGS. 7A to 7D and 8Ato 8D are respective transfer routes of the lower wafer W and the upperwafer W when the respective wafers W are transferred to the interior ofthe process module 13. From the viewpoint of improvement of throughput,it is preferable to linearly move the respective wafers W. In thisembodiment, each of the wafers W is moved along a curved route so as totransfer the wafer W toward the stages 15 a or 15 b through the shortestdistance while avoiding interference with the components and the likedisposed within the process module 13.

First, the lower wafer W and the upper wafer W are held by the transferarm 14 a while overlapping each other (a holding step) and the transferarm 14 is moved to the front of one process module 13 (FIG. 7A).Subsequently, the link mechanism of the transfer arm 14 a extends tomove the lower wafer W and the upper wafer W held by the pick part 24 atoward the stage 15 a (one of the mounting tables) via the communicationport 27 (a first transfer step). In this embodiment, since thelight-emitting part 29 a of the lower wafer detection sensor 29 isdisposed to be placed between the lower wafer W and the upper wafer Wand the light-receiving part 29 b is disposed to face the light-emittingpart 29 a with the lower wafer W interposed between the light-receivingpart 29 b and the light-emitting part 29 a, one point on the edgeportion of the lower wafer W first passes between the light-emittingpart 29 a and the light-receiving part 29 b of the lower wafer detectionsensor 29 (FIG. 7B). At this time, the passage of the lower wafer W isdetected and a position of the one point on the edge portion of thelower wafer W is specified.

Thereafter, when the lower wafer W is continuously transferred, thelight-emitting part 29 a is disposed in a region through which the lowerwafer W passes, so that the other point on the edge portion of the lowerwafer W passes between the light-emitting part 29 a and thelight-receiving part 29 b (FIG. 7C). At this time, this passage of thelower wafer W is also detected and a position of the other point on theedge portion of the lower wafer W is specified. Accordingly, thepositions of the two points on the edge portion of the lower wafer W arespecified. In general, when positions of two points on a circumferenceof a circle are specified and a radius r of the circle is known, asshown in FIG. 9, a vertex (black dot in FIG. 9) of an isosceles trianglehaving a line 1, which connects the two points (white dots in FIG. 9) ofwhich positions have been specified, as a base line and the radius r asa hypotenuse becomes a center of the circle. Therefore, even in thisembodiment, it is possible to specify a center position of the lowerwafer W based on the positions of two specified points on the edgeportion of the lower wafer W and the radius of the lower wafer W.Thereafter, the position of the lower wafer W is corrected based onmisalignment between the specified center position of the lower wafer Wand a desired center position of the lower wafer W. Specifically, evenafter the positions of the two points on the edge portion of the lowerwafer W are specified, the lower wafer W is continuously transferredtoward the stage 15 a (FIG. 7D). At this time, the position of the lowerwafer W is corrected. Thereafter, the lower wafer W is mounted on theupper surface of the stage 15 a.

Subsequently, due to the retraction of the link mechanism, the pick part24 a of the transfer arm 14 a is withdrawn from the interior of oneprocess module 13. At this time, the pick part 24 a holds only the upperwafer W (FIG. 8A). Thereafter, the link mechanism of the transfer arm 14a extends to move the upper wafer W toward the stage 15 b via thecommunication port 27 (a second transfer step). In this embodiment,since the upper wafer detection sensor 30 is disposed in a regionthrough which the upper wafer W passes when viewed from above along theoverlapping direction, one point on the edge portion of the upper waferW first passes between the light-emitting part 30 a and thelight-receiving part 30 b of the upper wafer detection sensor 30 (FIG.8B). At this time, the passage of the upper wafer W is detected and aposition of the one point of the upper wafer W is specified.

Thereafter, when the upper wafer W is continuously transferred, thelight-emitting part 30 a is disposed in a region through which the upperwafer W passes, so that the other point on the edge portion of the upperwafer W passes between the light-emitting part 30 a and thelight-receiving part 30 b (FIG. 8C). At this time, this passage of theupper wafer W is also detected and a position of the other point on theedge portion of the upper wafer W is specified. Accordingly, thepositions of the two points on the edge portion of the upper wafer W arespecified. Then, in the same manner as the center position of the lowerwafer W, it is possible to specify a center position of the upper waferW based on the positions of two specified points on the edge portion ofthe upper wafer W and the radius of the upper wafer W. Subsequently, theposition of the upper wafer W is corrected based on misalignment betweenthe specified center position of the upper wafer W and a desired centerposition of the upper wafer W. Specifically, even after the positions ofthe two points on the edge portion of the upper wafer W are specified,the upper wafer W is continuously transferred toward the stage 15 b(FIG. 8D). At this time, the position of the upper wafer W is corrected.Thereafter, the upper wafer W is mounted on the upper surface of thestage 15 b.

Subsequently, due to the retraction of the link mechanism, the pick part24 a of the transfer arm 14 a is withdrawn from the interior of oneprocess module 13. Then, the method is terminated.

According to the substrate processing apparatus 10 described above,since the light-emitting part 29 a of the lower wafer detection sensor29 is disposed to be placed between the lower wafer W and the upperwafer W when the lower wafer W is transferred toward the interior of theprocess module 13 and the light-receiving part 29 b is disposed to facethe light-emitting part 29 a with the lower wafer W interposed betweenthe light-receiving part 29 b and the light-emitting part 29 a, only thelower wafer W passes between the light-emitting part 29 a and thelight-receiving part 29 b. Accordingly, the lower wafer detection sensor29 can detect the edge portion of the lower wafer W, irrespective of thepresence of the upper wafer W. Moreover, since the light-emitting part29 a is disposed in the region through which the lower wafer W passeswhen the lower wafer W is transferred toward the interior of the processmodule 13, the edge portion of the lower wafer W passes twice betweenthe light-emitting part 29 a and the light-receiving part 29 b.Accordingly, it is possible to specify the positions of the two pointson the edge portion of the lower wafer W. Furthermore, since the upperwafer detection sensor 30 is disposed in the region through which theupper wafer W passes when the upper wafer W is transferred toward theinterior of the process module 13, the edge portion of the upper wafer Wpasses twice between the light-emitting part 30 a and thelight-receiving part 30 b of the upper wafer detection sensor 30.Accordingly, it is possible to specify the positions of the two pointson the edge portion of the upper wafer W. As a result, it is possible toaccurately specify the respective positions of the two wafers W disposedin the overlapping state by using the method of specifying the centerposition of the circle as shown in FIG. 9.

In the substrate processing apparatus 10, when the received amount ofthe laser light (or red LED light) 1 received by the light-receivingpart 29 b of the lower wafer detection sensor 29 falls below thepredetermined threshold value, since the light-received amount monitor35 issues the warning, which urges a user to pay attention to cleaning,to the controller 26 or issues the signal for requesting theinterruption of the transfer of the lower wafer W, it is possible toprevent a failure in specifying the position of the edge portion of thelower wafer W due to a decrease in the amount of the laser light (or redLED light) 1.

Although the embodiments of the present disclosure have been describedabove, the present disclosure is not limited to these embodiments.

For example, in the embodiments of the present disclosure, the method ofspecifying the center position of the lower wafer W and the method ofspecifying the center position of the upper wafer W when the lower waferW and the upper wafer W are transferred from the transfer module 12 tothe interior of the process module 13 (FIGS. 7A to 7D and 8A to 8D) havebeen described above. However, it is possible to specify the centerposition of the lower wafer W and the center position of the upper waferW by using the same method as that illustrated in FIGS. 7A to 7D and 8Ato 8D even when the lower wafer W and the upper wafer W are transferredfrom the interior of the process module 13 to the transfer module 12.Even in this case, the lower wafer W is first transferred and the upperwafer W is then transferred.

Furthermore, in the substrate processing apparatus 10, when the edgeportion of the lower wafer W passes between the light-emitting part 29 aand the light-receiving part 29 b, or when the edge portion of the upperwafer W passes between the light-emitting part 30 a and thelight-receiving part 30 b, a moving speed of the lower wafer W or theupper wafer W may be lowered. Thus, it is possible to enhance detectionsensitivity of the passage of each of the wafers W. In addition, afterthe lower wafer W has been subjected to the PHT processing as a heattreatment, it is preferable to lower a transfer speed of the lower waferW when the lower wafer W passes between the light-emitting part 29 a andthe light-receiving part 29 b of the lower wafer detection sensor 29.Accordingly, a deposition adhered to the light-emitting part 29 a or thelight-receiving part 29 b can be vaporized by radiant heat from thelower wafer W heated by the PHT processing, thereby maintaining thedetection sensitivity of the passage of the edge portion of the lowerwafer W. In particular, if the received amount of the laser light (orred LED light) 1 falls below the predetermined threshold value asdescribed above, the lower wafer W subjected to the PHT processing maybe temporarily stopped when the lower wafer W passes between thelight-emitting part 29 a and the light-receiving part 29 b. Accordingly,it is possible to sufficiently transfer radiant heat to the depositionadhered to the light-emitting part 29 a or the light-receiving part 29b, so that the deposition can be securely vaporized and removed.

In addition, a height sensor 36 for measuring a height of the pick part24 a of the transfer arm 14 a, in particular, a height of the wafer Wmounted on the pick part 24 a may be mounted on the load lock module 19a (FIG. 10). Therefore, it can be determined whether there is apossibility that the upper wafer W or the upper pick 24 at of the pickpart 24 a interferes with the light-emitting part 29 a of the lowerwafer detection sensor 29 due to lowering of the location of the pickpart 24 a of the transfer arm 14 a, which results from, for example,aging or an accident. Therefore, it is possible to prevent the upperwafer W and the like from interfering with the light-emitting part 29 a.

Further, the substrate processing apparatus 10 may have a monitor 37 fordisplaying a specified position of each wafer W to a user (FIG. 11). Themonitor 37 displays, for example, a graph 37 a in which positionalmisalignment from an ideal position of each wafer W is represented byoverlapping or a graph 37 b in which the amount of positionalmisalignment from the ideal position of each wafer W is represented intime series. Accordingly, the user can understand a tendency of thepositional misalignment and roughly estimate a cause of the occurrenceof the positional misalignment, so that it is possible to quicklycorrect future positional misalignment.

Further, in the substrate processing apparatus 10, the lower waferdetection sensor 29 specifies the positions of two points of the lowerwafer W and the upper wafer detection sensor 30 specifies the positionsof two points of the upper wafer W. However, for example, an edgeportion detection sensor different from the lower wafer detection sensor29 may be provided in the region through which the lower wafer W passesso as to allow each of the lower wafer detection sensor 29 and the edgeportion detection sensor to specify the position of one point of thelower wafer W. An edge portion detection sensor different from the upperwafer detection sensor 30 may be provided in the region through whichthe upper wafer W passes so as to allow each of the upper waferdetection sensor 30 and the edge portion detection sensor to specify theposition of one point of the upper wafer W.

A storage medium on which program codes of software for implementing thefunctions of the embodiments are recorded is provided to the controller26 included in the substrate processing apparatus 10 so that a CPU ofthe controller 26 reads and executes the program codes stored in thestorage medium, thereby achieving the object of the present disclosure.

In this case, the program codes themselves read from the storage mediumimplements the functions of the embodiments, and the program codes andthe storage medium storing the program codes constitute the presentdisclosure.

The storage medium for supplying the program codes may include anymedium capable of storing the program codes therein, for example, a RAM,an NV-RAM, a floppy (registered trademark) disk, a hard disk, amagneto-optical disk, an optical disk such as a CD-ROM, a CD-R, a CD-RW,a DVD (DVD-ROM, DVD-RAM, DVD-RW, DVD+RW), a magnetic tape, anon-volatile memory card, other ROMs and the like. Alternatively, theprogram codes may be supplied to the controller 26 by downloading themfrom a database or another computer (not shown) connected to theInternet, a commercial network, a local area network or the like.

Furthermore, the functions of the embodiments can be implemented byexecuting the program codes read by the controller 26, and an OS(operating system) running on the CPU may perform a portion or all ofactual processing based on instructions of the program codes so that thefunctions of the embodiments may be implemented by the processing.

Moreover, the program codes read from the storage medium may be writtenin a memory of a function extension board inserted into the controller26 or a function extension unit connected to the controller 26, and aCPU provided in the function extension board or the function extensionunit may perform a part or all of the actual processing based on theinstructions of the program codes so that the functions of theembodiments may be implemented by the processing.

The program codes may be in the format of object codes, program codesexecutable by an interpreter, script data supplied to an OS, or thelike.

According to the present disclosure, one of the light-emitting part andthe light-receiving part of the lower substrate detection sensor isdisposed to be placed between the lower substrate and the uppersubstrate when the lower substrate is transferred between one mountingable and the transfer chamber, and the other of the light-emitting partand the light-receiving part of the lower substrate detection sensor isdisposed to face one of the light-emitting part and the light-receivingpart with the substrate interposed between the light-emitting part andthe light-receiving part, so that only the lower substrate passesbetween the light-emitting part and the light-receiving part of thelower substrate detection sensor. This allows the lower substratedetection sensor to detect the edge portion of the lower substrateirrespective of the presence of the upper substrate. In addition, sinceone of the light-emitting part and the light-receiving part of the lowersubstrate detection sensor is disposed in the region through which thelower substrate passes when the lower substrate is transferred, the edgeportion of the lower substrate passes twice between the light-emittingpart and the light-receiving part of the lower substrate detectionsensor. Accordingly, it is possible to detect two points on the edgeportion of the lower substrate. Furthermore, since the upper substratedetection sensor is disposed in the region through which the uppersubstrate passes when the upper substrate is transferred between theother mounting table and the transfer chamber, the edge portion of theupper substrate passes twice in front of the upper substrate detectionsensor. Accordingly, it is possible to detect two points on the edgeportion of the upper substrate. As a result, it is possible toaccurately specify the position of each of the two substrates disposedin an overlapping state.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of the disclosures. Indeed, the embodiments described herein maybe embodied in a variety of other forms. Furthermore, various omissions,substitutions and changes in the form of the embodiments describedherein may be made without departing from the spirit of the disclosures.The accompanying claims and their equivalents are intended to cover suchforms or modifications as would fall within the scope and spirit of thedisclosures.

What is claimed is:
 1. A substrate processing apparatus having atransfer arm configured to transfer two substrates between a transferchamber and a processing chamber having two mounting tables, thetransfer arm holding the two substrates in a state where the twosubstrates overlap each other with a gap between the two substrates, thesubstrate processing apparatus comprising: a lower substrate detectionsensor configured to detect two points on an edge of a lower substrateof the two substrates and specify positions of the two points when thelower substrate is transferred, the two points being different from eachother; and an upper substrate detection sensor configured to detect anedge of an upper substrate of the two substrates when the uppersubstrate is transferred, wherein the transfer arm transfers the lowersubstrate between one of the mounting tables and the transfer chamberand transfers the upper substrate between the other of the mountingtables and the transfer chamber, the lower substrate detection sensor isan optical sensor having a light-emitting part and a light-receivingpart, one of the light-emitting part and the light-receiving part isdisposed in a region through which the lower substrate passes when thelower substrate is transferred, and is disposed to be placed between thelower substrate and the upper substrate, the other of the light-emittingpart and the light-receiving part is disposed to face the one of thelight-emitting part and the light-receiving part with the lowersubstrate interposed between the light-emitting part and thelight-receiving part when the lower substrate is transferred, the uppersubstrate detection sensor is disposed in a region through which theupper substrate passes when the upper substrate is transferred, and theone of the light-emitting part and the light-receiving part is installedwithin a communication port communicating an interior of the transferchamber with an interior of the processing chamber.
 2. The substrateprocessing apparatus of claim 1, wherein one of the light-emitting partand the light-receiving part is disposed in a reduced pressureatmosphere.
 3. The substrate processing apparatus of claim 1, furthercomprising a height sensor configured to measure a height of thetransfer arm.
 4. The substrate processing apparatus of claim 1, whereinthe transfer arm transfers the two substrates through an openingprovided between the processing chamber and the transfer chamber, and awidth of the opening is smaller than a total width of the two substrateswhen the two substrates are horizontally arranged.
 5. The substrateprocessing apparatus of claim 1, wherein the transfer arm moves therespective two substrates along curved routes.
 6. The substrateprocessing apparatus of claim 1, wherein the communication port issurrounded by a flange, the lower substrate detection sensor isinstalled in a cup-shaped bracket, and the cup-shaped bracket is mountedon a sensor port formed on the flange, the one of the light-emittingpart and the light-receiving part is held by a shim, and is bent in anL-shape to protrude from the bracket to an interior of the communicationport, and the other of the light-emitting part and the light-receivingpart is installed outside of and at a bottom of the bracket, and facesthe one of the light-emitting part and the light-receiving part via asensor window formed on the bracket.